Downstream of scrubbers (wet cleaners), for instance downstream of scrubbers of flue gases, up to now preheating means in the form of heat exchangers or by the direct application of is energy by means of gas burners have been used in order to transport the wet gas through large chimneys having a height of up to 400 m. In this manner, the ejection of coarse droplets from the chimney that fall down in the direct vicinity of the chimney should be avoided. However, these installations are very expensive and need an extensive maintenance or have a high energy consumption.
Accordingly, modern installations are equipped with so-called wet chimneys that have a height of about 250 m. Here, the gas transport occurs with the assistance of pressure increasing blowers upstream of or downstream of the scrubber. A high condensate generation results within the chimney on account of the cooling of the wet gas on the way to the exit of the chimney so that the ejection of coarse droplets from the chimney results that fall down in the direct vicinity of the chimney (installation, village). Up to now, apart from simple drainage means, only in few cases installations, as for instance axial cyclones, were provided in the large chimneys since the same result in very high energy losses on account of the high speeds in the chimney and up to now do not represent a satisfying solution with respect to the discharge of droplets.
Furthermore, so-called film traps or other baffles have been installed in many wet chimneys for the reduction of the droplet ejection. Such film traps prevent the entraining of liquid films along the chimney wall. However, these measures are normally only conditionally usable since the liquid film is entrained or droplets are dragged-out from the film on account of the high gas speeds in such chimneys. Accordingly, a detrimental droplet ejection cannot be completely prevented even with such installations.
From DE 298 15 970 U1 a chimney tube with inner profilation for a wet chimney is known wherein the condensation in the chimney tube is to be improved by the provided inner profilation etc.
In WO 95/12784 a condensation chimney is described wherein the wet, cold, condensing chimney has an outer chimney wall in the inner space of which an inner tube is arranged. A profile tube is used as inner tube in order to enlarge the contact surface for the flue gas.
From WO 95/04246 a chimney is known that is provided with a plurality of packings in order to increase the amount of condensate. The used packings are semi-spherically formed and realized as grid construction.